The present invention relates to a device for non-invasive determination of blood pressure in the veins and arteries of fingers and toes.
Vascular diseases belong to the most common diseases in humans. Among these are, in particular, arteriosclerosis (calcium or fatty deposits in the arteries), dilation of veins (varicose veins) or vein blockage (thrombosis). There has been a need for a simple, bloodless method for determining the blood pressure especially in fingers and toes, because hemodynamic disturbances caused by the afore-mentioned diseases can already be detected in the early stages.
There are numerous state-of-the-art methods for measuring the peak (systolic Ps), bottom (diastolic Pd) or the average blood pressure of the arterial system, respectively during its temporal course. They all have in common that first a pressure-buildup band applied to the section of the limb (e.g., upper arm or finger) is quickly inflated in such a manner that its pressure Po exceeds Ps within a few seconds. At this moment the outside pressure on the vessels beneath is greater than the pressure within them: they are closed. A slow reduction of Po follows. Lowering Po under Ps permits a restricted flow of blood which causes the pulsating effect (e.g. Korotkoff tones in Riva-Rocci methods, pressure oscillation in the band in oscillometric methods or the return of pulsation in the reflection, respectively transmission signal in the photoplethysmographic method) known in the state of the art.
The primary drawback of these processes is that it is impossible to determine the blood pressure Pv in the veins in this manner, which is of decisive significance for diagnosis.
In healthy humans in a prostrate position, the vein system may be termed. "low pressure system", i.e. the vein pressure Pv only amounts to a few mmHg. When the venous blood flow between the measurement area and the heart is obstructed, e.g. in the case of acute thrombosis in the veins of the legs, the pressure Pv, on the other hand, is raised. In an upright position, the hydrostatic pressure components are added to these horizontal vein pressure values in the gravitational field of the earth so that the vein pressure in the lower parts of the body can increase substantially due to the redistribution of the blood volumes.
The object of the present invention is to provide a measurement device for non-invasive determination of blood pressure in the peripheral veins and arteries. An invented solution to this object with its improvements is set forth in the claims hereto. It is successful on the basis of a surprisingly simple fundamental idea: the reversal of the hitherto customary pressure process. Instead of the state-of-the-art procedure, rapid pressure buildup in the measurement band to Po&gt;Ps and measured value search in the following measurement phase with slow pressure reduction, according to the present invention the pressure in the band is first built up slowly from 0 mmHg. The blood pressure values Pv, Pd and Ps are already determined in this preferably linear pressure build-up phase.
The present invention is made more apparent in the following using preferred embodiments with reference to the accompanying drawings to which moreover is to be referred for all invented details not made apparent in the text, without the intention of limiting the scope and spirit of the overall inventive idea.